Dust-removing attachment device for power grinders

ABSTRACT

A dust-removing attachment device for rotary disk power grinders or sanders is described wherein a continuous current of air is maintained over and around the grinding or sanding surface to capture and withdraw dust particles and the like into a vacuum chamber. Filtered and pressurized exhaust air from a vacuum cleaner tank is directed through a first plenum to discharge forcefully about the rotary disk at one side, and a vacuum plenum open at the other side of the disk and leading to the input of the vacuum cleaner serves to maintain a strong current of dust capturing circulating air.

United States Patent Quintana 5] Mar. 7, 1972 [54] DUST-REMOVING ATTACHMENT DEVICE FOR POWER GRINDERS 21 Appl. No.: 66,284

FOREIGN PATENTS OR APPLICATIONS 17,447 7/1914 GreatBritain.... .....51/273 515,792 12/1939 GreatBritain ..51/273 Primary Examiner-William R. Armstrong Attorney-Ernest H. Schmidt ABSTRACT A dust-removing attachment device for rotary disk power grinders or sanders is described wherein a continuous current of air is maintained over and around the grinding or sanding surface to capture and withdraw dust particles and the like into a vacuum chamber. Filtered and pressurized exhaust air from a vacuum cleaner tank is directed through a first plenum to discharge forcefully about the rotary disk at one side, and a vacuum plenum open at the other side of the disk and leading to the input of the vacuum cleaner serves to maintain a strong current of dust capturing circulating air.

10 Claims, 4 Drawing Figures PATENTEDMAR 7 I912 3,646,712

' .3 BY EHSMAk DUST-REMOVING ATTACHMENT DEVICE FOR POWER GRINDERS This invention relates to attachment devices for power grinders or sanders, and is directed particularly to an attachment device for manually controlled grinders or sanders operative to continuously withdraw sanded or ground-away dust particles and the like into a collection chamber to substantially eliminate air pollution as a result of such sanding or grinding.

it is well known that motorized grinding and sanding tools, particularly those having high-speed rotary sanding or grinding elements, throw off large volumes of abraded, sanded or ground-away dustlike particles in their operation, under the influence of centrifugal force. Such particles generally spin out in all directions, so that the surrounding air quickly becomes heavily polluted. Depending upon what material is being worked upon in the grinding or sanding operation, such pollution presents a substantial health hazard to the operator of the grinding tool and even to others in the surrounding area. Grinding and sanding hazards are particularly evident, for example, in automotive body and paint shops wherein the grinding and sanding of paint, metals and synthetic filler resins constitutes a major part of the work being done. Various measures taken to alleviate the effects of such air pollution, for example the use of dust-filtering face masks, air blowers and the like, while of some value in reducing the pollution, have been found to be only partially effective.

It is, accordingly, the principal object of this invention to obviate the above-described deficiencies of antipollution measures heretofore resorted to in the use of power grinding tools.

A more particular object of the invention is to provide a dust-removing attachment device for power grinders or sanders that provides strong, continuous current of air over and around a grinding or sanding surface in such a manner that substantially all of the particles being sanded or ground away will be captured and withdrawn into a vacuum chamber.

Still another object of the invention is to provide a dustremoving attachment device of the above nature which will be readily attachable to an ordinary manually controlled motorized disk sander or grinder, and which includes a pressurized air plenum operative to discharge air under pressure through peripheral jet openings along one side of the rotary disk, and a vacuum plenum open at the other side of the disk and somewhat forewardly of the air pressure jets to recapture the discharged pressurized air after it has passed over and around the rotary sanding or grinding disk together with sanded or ground away particles entrapped within the strong current of surrounding airflow thus provided.

Yet another object of the invention is to provide a dustremoving attachment device of the character described which can readily be operated with a remotely located commercialtype tank vacuum by the use of lightweight interconnecting vacuum and pressure hoses so as to minimize any interference or inconvenience in the use of an associated manually controlled sander or grinder.

Still another object of the invention is to provide a dust removing attachment device of the character described which will be simple in construction, inexpensive to manufacture, light in weight, durable in use, and readily adaptable to rotary disk sanders and grinders of various sizes and design.

Other objects, features and advantages of the invention will be apparent from the following description when read with reference to the accompanying drawings. in the drawings, wherein like reference numerals denote corresponding parts throughout the several views:

F [G 1 illustrates, in side elevation, a typical, manually operated power grinder equipped with a dust-removing attachment device embodying the invention;

FIG. 2 is a bottom view of the power grinder and dustremoving attachment device assembly;

FIG. 3 is a vertical cross-sectional view of the attachment device, taken along the line 3-3 of FIG. 2 in the direction of the arrows; and

HG. 4 is a transverse cross-sectional view taken along the line 4-4 of FIG. 3 in the direction of the arrows.

Referring first to FIG. 1, there is illustrated therein a preferred form of attachment device for rotating disk power grinders or sanders, designated generally by reference numeral 10, shown assembled for use in association with a typical manually controlled portable power grinder G. The attachment device 10 is operative to pneumatically collect and withdraw ground, sanded or abraded away particles of the workpiece being operated upon during use of the grinder by a closed-circuit flow of air surrounding the grinder disk and carrying away such dust and airborne particles into an associated vacuum tank T through a vacuum hose 12. The filtered exhaust air from the vacuum tank T is discharged to the attachment device 10 in the manner and for the purpose hereinafter more particularly described to complete the airflow cycle by means of which substantially all of the sanded or ground-away dustlike material particles are carried to the vacuum tank T to minimize air pollution in the vicinity of grinding or sanding operations.

A typical manually held and controlled electric grinder G with which the dust-removing attachment device 10 embodying the invention is particularly well suited for use comprises a motor housing 13 having a handgrip handle 14 at one end provided with a trigger switch 15 for setting the motor into operation, and a second handle grip bar 14a. At the other end of the motor housing 13 is a right-angularly directed cylindrical drive shaft bearing housing portion 16 centrally journaling a rotary drive shaft 17 which, at its inner end may be provided with diametrically opposed flats 18 (only one illustrated) for the purpose hereinafter appearing. The drive shaft 17 extends outwardly into a reduced-diameter, threaded end portion 19. Threadingly received on the threaded outer end portion of the drive shaft 19 is a shallow, frustoconical grinding disk support plate 20, said support plate being provided with a central, internally threaded boss 21 for this purpose. it will be understood that when threaded securely in place, the outer end of the internally threaded boss 21 of the grinding disk support plate 20 will seat securely against the outer end of the increased-diameter portion 17 of the drive shaft, the thread direction being such that the rotational direction of such shaft will tend to maintain the disk support plate in threaded-on assembled relation. The grinding disk support plate 20 is formed in its outer surface with a circular recess 22 through which the threaded drive shaft end portion 19 extends, said drive shaft end portion extending somewhat short of the outer surface of said disk support plate 20, however.

Means is provided for removably securing centrally apertured grinding or sanding disks in face-to-face engagement against the outer surface of the grinding disk support plate 20. To this end, there is provided a circular retainer disk 23, integrally formed with a central, inwardly extending, internally threaded boss portion 24 adapted to be threaded down upon the outwardly extending portion of the drive shaft end portion 19. The circular retainer disk 23 serves to clarnpingly engage in place central zone portions of a thin grinding or sanding disk member 25 circumjacently placed upon the drive shaft end portion 19. To facilitate removal and replacement of the circular retainer disk 23 when changing grinding or sanding disks 25, the outer face of said retainer disk is provided with a pair of diametrically opposed, cylindrical recesses 26 for the reception of a spanner-type wrench.

The dust-removing attachment device 10, which may, for example, be integrally molded for the most part of a tough, rigid, shock-resistant synthetic plastic material for economy of manufacture and lightness in weight, comprises a substantially circular collar portion 27 of such diameter and length as to fit snugly over the cylindrical portion 16 of the grinder housing to which it is attached. The collar portion 27 is longitudinally slotted at one side to define opposed end portions integrally formed with spaced, parallel, outwardly extending lug members 29, 30 centrally drilled to receive a bolt and nut 30a by means of which said collar portion can be securely clamped in place. The outer edge of the circular collar portion 27 merges with an outwardly inclined, frustoconical body portion 31 the outer diameter of which will be approximately the same as or slightly greater than that of the disk support plate 20. The outer peripheral edge of the body portion 31 is integrally formed with a peripherally extending arcuate airflow chamber 32, which may be of substantially rectangular cross section and which is directed to the rear of said conical body portion. The airflow chamber 32 is formed with a comparatively thick front wall portion 33,. a peripheral outer sidewall portion 34 and a spaced, parallel, circular inner sidewall portion 34a. The peripheral outer sidewall portion 34 of the airflow chamber 32 merges with opposed, tangentially convergent sidewall portions 35, 36 (see FIG. 2), which terminate in outwardly extending spaced, parallel, inlet opening sidewall portion 37, 38, respectively. The airflow chamber 32 further comprises an annular rear wall portion 39 (see FIG. 3) which merges with a rear pressurized air chamber wall 40 extending between and enclosing the opposed, tangential, sidewall portions 35 and 36 and the spaced, parallel end wall portions 37, 38. Similarly, a front pressurized air chamber wall 41 extends between the outer end portion of the opposed tangential side portions 35, 36 and the spaced parallel sidewall portions 37, 38 to define therewith and with the back pressurized air chamber wall 40 a plenum 40a for the reception of pressurized air as is hereinafter more particularly described. In this connection the outer peripheral sidewall portion 34 of the airflow chamber 32 does not extend beyond the zones of tangential merging of the sidewall portions 35, 36 with said peripheral sidewall portion so as to provide free passage of pressurized air entering the above-described air plenum into the arcuate airflow chamber 32. As illustrated in FIGS. 2, 3 and 4, the front wall portion 33 of the arcuate airflow chamber 32 is provided along its length with a plurality of equidistantly spaced vent openings 42 inclined inwardly in substantially radial directions with respect to the rotational axis of the drive shaft 19. The vent openings extend approximately halfway about the outwardly extending portion of the airflow chamber 32, i.e., that portion thereof opposite the pressurized air plenum 40a. The outer end portions of the back and front air chamber walls 40 and 41, respectively, together with the end wall portions 37 and 38, define a substantially rectangular pressurizedair inlet opening 43 for the reception and connection thereto of the pressurized airhose 11, as is hereinbelow more particularly described.

The opposed tangential sidewall portions 35, 36 together with their respective end wall portions 37 and 38 merge with like, forwardly extending, opposed sidewall portions 44, 45 the outer ends of which merge with a bridging vacuum chamber outer wall 46 in spaced parallel relation with respect to the pressurized air chamber wall 41. The inner end of the outer wall 46, as is best illustrated in FIG. 2, is provided with an arcuate recess 48 lying along a circle substantially concentric with the rotational axis of the drive shaft 19 and having a radius slightly greater than that of the disk support plate 20. The vacuum chamber outer wall 46 together with the opposed sidewall portions 44, 45 and the front pressurized air chamber wall 41 define a vacuum plenum 46a having, directly to the front of the pressurized inlet air opening 43, a substantially rectangular vacuum chamber opening 47. With reference to FIG. 3, it will be noted that the pressurized air plenum 40a and its associated airflow chamber 32 is disposed in spaced parallel relation to the rear of the outer face of the grinding disk support plate 20, whereas the vacuum chamber plenum 46a is deep enough to encompass an arcuate zone at its inlet opening that extends from behind said grinding disk support plate to a substantial distance to the front or forewardly of said grinding disk support plate.

Means is provided for removably connecting the outer ends of pressurized airhose 11 and the vacuum hose 12 to their respective air inlet opening and vacuum outlet opening 43 and 47, respectively. To this end, the outer ends of said hoses are formed into such rectangular shape that they-will fit snugly within their respective rectangular openings, and said outer end portions are provided with laterally opposed detent opening pairs 49, 49 and 50, 50, respectively, for the reception of spring-pressed retainer pins 51 and 52 yieldably supported by leaf spring 53, 54 (see FIGS. 1 and 2), the remote ends of which springs are attached, such as by rivets 55, to opposed sidewall portions 44, 45 of the vacuum plenum 46a. It will be understood that removal of the hoses can be simply effected by pulling outwardly on the spring release knobs 56, 57 to simultaneously free the connected ends of the pressurized air and vacuum hoses 11 and 12, respectively.

In use of the dust-removing attachment device 10, the pressurized airhose l 1 will be connected with a source of air under pressure, which may conveniently be the exhaust port of an ordinary commercial vacuum tank T, and the vacuum hose 12 will be connected with the inlet or vacuum port of the tank. It will be understood that the hoses 11 and 12 will be of a highly flexible and lightweight material, and long enough to permit full freedom of use of the grinding tool to which the dustremoving device is attached. With references to FIGS. 2 and 3 it will be noted how pressurized air will flow under pressure through the pressurized air vent openings 42 both over and under the outer and inner faces of the rotating grinding disk support plate 20 and its associated grinding or sanding disk 25 in the direction of the forward arcuate opening 48 of the vacuum chamber plenum 46a. The forced airflow through the inwardly directed vent openings 42 in its passage around, be-

hind and in front of the rotating grinding or sanding disk 25 is given added impetus by the reduced air pressure in the vicinity of the arcuate front opening of the vacuum chamber plenum 46a, and thereby serves to maintain the integrity of the circulating air passage around and about the rotating grinding or sanding disk 25 when the grinder G is in operation so as to capture and withdraw through said vacuum plenum chamber and the vacuum hose 12 substantially all of the sanded or abraded dust particles being removed from the workpiece. It is to be noted that while the rotating grinding disk support plate 20 and its associated grinding or sanding disk will have a strong tendency to throw off such particles and dust under the impetus of centrifugal force, the velocity of airflow enveloping the grinding disk support plate as is described above can readily be made strong enough to entrap and carry such outwardly projected dust particles into the vacuum plenum 46a for removal and collection in the vacuum tank T.

While I have illustrated and described herein only one form in which my invention can conveniently be embodied in practice, it is to be understood that this form is presented by way of example only and not in a limiting sense. For example, although the attachment device is illustrated and described herein for use with a rotary grinder, the inventive concept is applicable as well to other types of grinding sanding tools such as motorized reciprocating plate sanding or grinding tools. The invention, in brief, comprises all the modifications and embodiments coming within the scope and spirit of the following claims.

What I claim as new and desire to secure by Letters Patent l. A dust-removing attachment device for rotary disk power grinder tools and the like comprising, in combination, a pressurized air plenum, means for removably securing said pressurized air plenum with respect to the tool, an airflow chamber means extending arcuately about one side of the tool rotary disk, said pressurized air plenum being fixed with respect to and communicating with said airflow chamber means, a plurality of vent openings in said airflow chamber means for directing air forcefully outwardly at one side of the tool rotary disk, a vacuum plenum fixed with respect to said pressurized air plenum and having an opening at the other side of the tool rotary disk, and means for supplying air under pressure to said pressurized air plenum and to produce a vacuum in said vacuum plenum for establishing a strong circulation of air over and about the tool rotary disk from said one side thereof to the other.

2. A dust-removing attachment device as defined in claim 1, wherein said means for supplying air under pressure comprises a flexible pressurized airhose and means for removably connecting one end of said pressurized airhose to said pressurized air plenum, and wherein said means for producing a vacuum in said vacuum plenum comprises a vacuum hose and means for removably connecting one end of said vacuum hose to said vacuum plenum.

3. A dust-removing attachment device as defined in claim 2, wherein said opening at said other side of said rotary disk tool is arcuate in shape and wherein said plurality of vent openings are operative to direct the pressurized air substantially in radial directions with respect to the axis of rotation of said rotary disk tool.

4. A dust-removing attachment device as defined in claim 2, wherein said means for removably securing said pressurized air plenum with respect to said tool comprises a collar member, means for securing said collar member about the rotary drive shaft housing of the tool, and a frustoconical body portion extending outwardly of said collar member, said pressurized air plenum and said airflow chamber means being integrally formed with said frustoconical body portion in surrounding relation with respect to the outer periphery thereof.

5. A dust-removing attachment device as defined in claim 4, wherein said airflow chamber means comprises an arcuate conduit extending rearwardly of said outer peripheral edge of said frustoconical body portion.

6. A dust-removing attachment device as defined in claim 5, wherein said pressurized air plenum extends rearwardly of said outer peripheral edge of said frustoconical body portion.

7. A dust-removing attachment device as defined in claim 6, wherein said vacuum plenum extends forwardly of said outer peripheral edge of said frustoconical body portion.

8. A dust-removing attachment device as defined in claim 7, wherein said opening at said other side of said rotary disk tool is arcuate in shape and wherein said plurality of vent openings are operative to direct the pressurized air substantially in radial directions with respect to the axis of rotation of said rotary disk tool.

9. A dust-removing attachment device as defined in claim 8, wherein said means for removably connecting said one end of said pressurized airhose to said pressurized air plenum, and said means for removably connecting said one end of said vacuum hose to said vacuum plenum, comprise opposed sidewall openings in each of said hose ends and spring-pressed retainer pins yieldingly fixed with respect to said vacuum plenum and operative to fit in said opposed sidewall openings.

10. A dust-removing attachment device as defined in claim 9, wherein said means for supplying under pressure to said pressurized air plenum and to produce a vacuum in said vacuum plenum comprises a vacuum cleaner having a vacuum input port connected with the other end of said vacuum hose and a pressurized exhaust air output port connected with the other end of said pressurized air hose. 

1. A dust-removing attachment device for rotary disk power grinder tools and the like comprising, in combination, a pressurized air plenum, means for removably securing said pressurized air plenum with respect to the tool, an airflow chamber means extending arcuately about one side of the tool rotary disk, said pressurized air plenum being fixed with respect to and communicating with said airflow chamber means, a plurality of vent openings in said airflow chamber means for directing air forcefully outwardly at one side of the tool rotary disk, a vacuum plenum fixed with respect to said pressurized air plenum and having an opening at the other side of the tool rotary disk, and means for supplying air under pressure to said pressurized air plenum and to produce a vacuum in said vacuum plenum for establishing a strong circulation of air over and about the tool rotary disk from said one side thereof to the other.
 2. A dust-removing attachment device as defined in claim 1, wherein said means for supplying air under pressure comprises a flexible pressurized airhose and means for removably connecting one end of said pressurized airhose to said pressurized air plenum, and wherein said means for producing a vacuum in said vacuum plenum comprises a vacuum hose and means for removably connecting one end of said vacuum hose to said vacuum plenum.
 3. A dust-removing attachment device as defined in claim 2, wherein said opening at said other side of said rotary disk tool is arcuate in shape and wherein said plurality of vent openings are operative to direct the pressurized air substantially in radial directions with respect to the axis of rotation of said rotary disk tool.
 4. A dust-removing attachment device as defined in claim 2, wherein said means for removably securing said pressurized air plenum with respect to said tool comprises a collar member, means for securing said collar member about the rotary drive shaft housing of the tool, and a frustoconical body portion extending outwardly of said collar member, said pressurized air plenum and said airflow chamber means being integrally formed with said frustoconical body portion in surrounding relation with respect to the outer periphery thereof.
 5. A dust-removing attachment device as defined in claim 4, wherein said airflow chamber means comprises an arcuate conduit extending rearwardly of said outer peripheral edge of said frustoconical body portion.
 6. A dust-removing attachment device as defined in claim 5, wherein said pressurized air plenum extends rearwardly of said outer peripheral edge of said frustoconical body portion.
 7. A dust-removing attachment device as defined in claim 6, wherein said vacuum plenum extends forwardly of said outer peripheral edge of said fruStoconical body portion.
 8. A dust-removing attachment device as defined in claim 7, wherein said opening at said other side of said rotary disk tool is arcuate in shape and wherein said plurality of vent openings are operative to direct the pressurized air substantially in radial directions with respect to the axis of rotation of said rotary disk tool.
 9. A dust-removing attachment device as defined in claim 8, wherein said means for removably connecting said one end of said pressurized airhose to said pressurized air plenum, and said means for removably connecting said one end of said vacuum hose to said vacuum plenum, comprise opposed sidewall openings in each of said hose ends and spring-pressed retainer pins yieldingly fixed with respect to said vacuum plenum and operative to fit in said opposed sidewall openings.
 10. A dust-removing attachment device as defined in claim 9, wherein said means for supplying under pressure to said pressurized air plenum and to produce a vacuum in said vacuum plenum comprises a vacuum cleaner having a vacuum input port connected with the other end of said vacuum hose and a pressurized exhaust air output port connected with the other end of said pressurized air hose. 